Scum is an integral component of solids management in MWWTP and is composed of fats, oils, grease and other entrained floatable materials that are collected during primary clarification. Lab scale BMP tests showed the addition of 14.5 g VS/L of scum exhibited the greatest increase in biogas production of 1.6 times per g VS added compared to the control, while a higher additional scum loading of 33.7 g VS/L reduced the biogas yield to 32% of the control reactor. Lab scale semi-continuous digestion measured the effects of scum loading and temperature of pretreatment in the scum concentrator. At 15 d and 20 d HRTs the greatest observed improvement in biogas was achieved by adding 3% scum by volume and pretreating the scum at 70°C in a scum concentrator with respective improvements of 24% and 16%.

Anaerobic digestion is a sustainable and economically feasible waste management technology, which lowers the emission of greenhouse gases (GHGs), decreases the soil and water pollution, and reduces the dependence on fossil fuels. The present thesis investigates the anaerobic digestion of waste from food-processing industries, including citrus wastes (CWs) from juice processing and chicken feather from poultry slaughterhouses. Juice processing industries generate 15–25 million tons of citrus wastes every year. Utilization of CWs is not yet resolved, since drying or incineration processes are costly, due to the high moisture content; and biological processes are hindered by its peel oil content, primarily the D-limonene. Anaerobic digestion of untreated CWs consequently results in process failure because of the inhibiting effect of the produced and accumulated VFAs. The current thesis involves the development of a steam explosion pretreatment step. The methane yield increased by 426 % to 0.537 Nm3/kg VS by employing the steam explosion treatment at 150 °C for 20 min, which opened up the compact structure of the CWs and removed 94 % of the D-limonene. The developed process enables a production of 104 m3 methane and 8.4 L limonene from one ton of fresh CWs. Poultry slaughterhouses generate a significant amount of feather every year. Feathers are basically composed of keratin, an extremely strong and resistible structural protein. Methane yield from feather is low, around 0.18 Nm3/kg VS, which corresponds to only one third of the theoretical yield. In the present study, chemical, enzymatic and biological pretreatment methods were investigated to improve the biogas yield of feather waste. Chemical pretreatment with Ca(OH)2 under relatively mild conditions (0.1 g Ca(OH)2/g TSfeather, 100 °C, 30 min) improved the methane yield to 0.40 Nm3/kg VS, corresponding to 80 % of the theoretical yield. However, prior to digestion, the calcium needs to be removed. Enzymatic pretreatment with an alkaline endopeptidase, Savinase®, also increased the methane yield up to 0.40 Nm3/kg VS. Direct enzyme addition to the digester was tested and proved successful, making this process economically more feasible, since no additional pretreatment step is needed. For biological pretreatment, a recombinant Bacillus megaterium strain holding a high keratinase activity was developed. The new strain was able to degrade the feather keratin which resulted in an increase in the methane yield by 122 % during the following anaerobic digestion. / <p>Akademisk avhandling som för avläggande av teknologie doktorsexamen vid Chalmers tekniska högskola försvaras vid offentlig disputation den 1 juni 2012, klockan 10.00 i KA-salen, Kemigården 4, Göteborg.</p>

Biogas production from organic materials can be used as a renewable vehicle fuel, provide heat and generate electricity and can thereby reduce the greenhouse gas emissions. This thesis focuses on the biogas production based on lignocelluloses. There is an abundant availability of lignocelluloses, constituting 50% of the total biomass worldwide. However, the biomass recalcitrance limits the microbial degradation as well as the biogas production from these types of materials. In the present work different pretreatment methods have been performed in order to decrease the biomass recalcitrance and improve the biogas production. Steam explosion pretreatment, together with the addition of sodium hydroxide and hydrogen peroxide, has been performed on lignocellulosic-rich paper tube residuals. The pretreatment has resulted in methane yields of up to 493 NmL/gVS, which is an increase by 107% compared with untreated material. Furthermore, the use of an organic solvent, N-methylmorpholine-N-oxide (NMMO), was evaluated as a pretreatment method for spruce (both chips and milled), rice straw, and triticale straw. The NMMO pretreatment resulted in 202, 395, 328, and 362 NmL CH4/g carbohydrates produced of these substrates, respectively, corresponding to an increase of between 400-1,200% compared with the untreated version of the same material. Moreover, the paper tube residuals have been co-digested with an unstable nitrogen-rich substrate mixture, mainly based on municipal solid waste. The addition of the lignocellulosic-rich paper tubes in a co-digestion process showed stabilizing effects and prevented the accumulation of volatile fatty acids with a subsequent reactor failure. Additionally, synergistic effects have been found leading to between 15-33% higher methane yields when paper tubes were added to the co-digestion process compared with the yields calculated from the methane potentials of the two substrates. Substrate characterization analysis can be used to study the changes on the lignocellulosic components after the pretreatment, relating the changes to the performance in the anaerobic digestion. Increased accessible surface area, measured by the Simons’ stain and the enzymatic adsorption methods, as well as decreased crystallinity, determined by using the Fourier Transform Infrared Spectroscopy, can all be linked to improved biogas production after pretreatment. Finally, the NMMO pretreatment on forest residues has been financially evaluated for an industrial scale process design. The base case that was evaluated simulated a case where pretreated forest residues were co-digested with the organic fraction of municipal solid waste to obtain optimal nutritional balance for the anaerobic digestion. This process has been found to be economically feasible with an internal rate of return of 20.7%. / <p>Akademisk avhandling som för avläggande av teknologie doktorsexamen vid Chalmers tekniska högskola försvaras vid offentlig disputation den 24 maj 2013, klockan 10.00 i KA,Kemigården 4, Göteborg</p>

The application of anaerobic digestion technology is growing worldwide, mainly because of its environmental benefits. Nevertheless, anaerobic degradation is a rather slow and sensitive process. One of the reasons is the recalcitrance nature of certain fractions of the substrate (e.g., lignocelluloses) used for microbial degradation; thus, the hydrolysis becomes the rate-limiting step. The other reason is that the degradation of organic matter is based on a highly dynamic, multi-step process of physicochemical and biochemical reactions. The reactions take place in a sequential and parallel way under symbiotic interrelation of a variety of anaerobic microorganisms, which all together make the process sensitive. The first stage of the decomposition of the organic matter is performed by fast growing (hydrolytic and acid forming) microorganisms, while in the second stage the organic acids produced are metabolized by the slow growing methanogens, which are more sensitive than the acidogens; thus, methanogenesis becomes the rate-limiting step. The first part of this work evaluates the effects of a pretreatment using an organic solvent, N-methylmorpholine-N-oxide (NMMO), on cellulose-based materials in order to overcome the challenge of biomass recalcitrance and to increase the rate of the hydrolysis. NMMO-pretreatment of straw separated from the cattle and horse manure resulted in increased methane yields, by 53% and 51%, respectively, in batch digestion tests. The same kind of pretreatment of the forest residues led to an increase by 141% in the methane production during the following batch digestion assays. The second part of this work evaluates the efficacy of a two-stage process to overcome the second challenge with methanogenesis as the rate-limiting step, by using CSTR (continuous stirred tank reactors) and UASB (up flow anaerobic sludge blanket) on a wide variety of different waste fractions in order to decrease the time needed for the digestion process. In the two-stage semi-continuous process, the NMMO-pretreatment of jeans increased the biogas yield due to a more efficient hydrolysis compared to that of the untreated jeans. The results indicated that a higher organic loading rate (OLR) and a lower retention time could be achieved if the material was easily degradable. Comparing the two-stage and the single-stage process, treating the municipal solid waste (MSW) and waste from several food processing industries (FPW), showed that the OLR could be increased from 2 gVS/l/d to 10 gVS/l /d, and at the same time the HRT could be decreased from 10 to 3 days, which is a significant improvement that could be beneficial from an industrial point of view. The conventional single stage, on the other hand, could only handle an OLR of 3 gVS/l/d and HRT of 7 days.

Fruits are among the most important commodities in global trading due to its fundamental nutritional values. In 2012, the fruits supply was 115 kg/person/year, however, only 50 % of the fruits reached their consumers and the rest ended up as waste during the long fruit supply chain. The waste from fruits is mostly dumped or burned, creating a serious environmental problem. A more sustainable handling of the waste is therefore highly desirable. One of them is conversion of the fruits wastes into biogas through anaerobic digestion. One challenge with the conversion of fruits wastes into biogas is the presence of antimicrobial compounds in the fruits, which reduce the biogas yield or even cause a total failure of the process. Fruit flavors have been reported to have antimicrobial activity against several microorganisms and being responsible for the defense system in the fruits. However, there is only scarce information about the effect of fruit flavors on anaerobic digesting microbia. The objectives of the present thesis were: 1) to investigate the inhibitory activity of the fruit flavors on anaerobic digestion; 2) to remove the flavor compound by pretreatment; and 3) to protect the cell from the flavor compounds using a membrane bioreactor. The inhibitory activity of the fruit flavors was examined from different groups of flavors by adding a single flavor compound into the batch anaerobic digesting system, at three different concentrations. Among the flavors added, myrcene and octanol were found to exhibit a strong inhibitory activity, with 50 % reduction of the methane production at low concentrations, ca. 0.005–0.05 %. These flavors can be found in oranges, strawberries, grapes, plums, and mangoes. The other flavors tested showed moderate and low inhibitory activity, which might not affect the anaerobic digestion of the fruits wastes. In order to overcome the inhibitory effects of the fruit flavor, two approaches were proposed in this thesis, namely, fruit flavor removal by leaching pretreatment and cell protection from fruit flavor using a membrane bioreactor. Orange peel waste and D-limonene were used as a model of fruit waste and inhibitor, respectively. The leaching pretreatment uses solvent to extract the limonene from the orange peel. The methane yield increased by 356 % from 0.061 Nm3/kg VS to 0.217 Nm3/kg VS, by pretreating the peel using hexane with peel and a hexane ratio of 1:12 at room temperature for 10 min. Alternative to limonene removal, the cells were encased in a hydrophilic membrane, which is impermeable to hydrophobic limonene. This method yielded more than six times higher methane yield, compared to the free cell. At the highest organic loading rate, examined in this work, 3 g VS/L/day, the methane yield of the reactor containing the free cell was only 0.05 Nm3/kg VS, corresponding to 10 % of the theoretical yield, whereas 0.33 Nm3/kg VS methane yield was achieved using a membrane bioreactor corresponding to 75 % of the theoretical yield. / <p>Thesis for the degree of Doctor of Philosophy at the University of Borås to be publicly defended on November 27th 2014, 10.00 a.m. in room E310, University of Borås, Allégatan 1, Borås.</p>

Dance has attracted little scientific interest on the effects of physical fitness improvements on performance and injury severity, particularly with respect to contemporary dance. The main aims of the current work were: a) to observe the physical demands of dance performance; b) to develop a reliable dance-specific performance tool; c) to assess the association between selected physical fitness parameters and performance in contemporary dance by using a new reliable method (AC test); d) to assess selected physical fitness parameters in relation to injury severity in contemporary dance; e) to study the effects of increased fitness parameters on performance through a randomized controlled trial. A total of 50 performances, performed by 20 dancers, were monitored by using a portable accelerometers (SWA armbands) and heart rate monitors while 45 performances in DVDs were video analysed. Six dancers and two dance teachers were recruited to test a newly developed performance tool. A sample made of 41 dancers were recruited and assessed for aerobic fitness (DAFT), lower body muscular power (jump height test), upper body muscular endurance (press-ups test), flexibility (active and passive hip ROM), body composition (skinfolds), performance (n=17) and injury severity (n=16). In order to investigate the effects of the supplementary fitness training on performance, 24 of the total 41 dancers, were randomly assigned to either an intervention (n=12) or control (n=12) group. The intervention group undertook a specifically designed exercise-training programme (circuit and WBV training) lasting six weeks. Both groups were re-tested for physical fitness levels and performance at the end of the intervention period. Results revealed that performance intensities varied from light to moderate while these were observed with the use of pliés and jumps as well as lifting other dancers. Based on the seven most frequently used criteria by selected pre-professional contemporary dance institutions and companies, a novel performance tool (AC tool) was developed with an inter-rater reliability of r=0.96. There was a significant correlation between aesthetic competence (AC) scores and jump ability (r=0.55) and press-ups (r=0.55), respectively. Stepwise backward multiple regression analysis revealed that the best predictor of AC was press-ups (R2=0.30, p=0.03, 95% confidence intervals=0.11–1.34). Univariate analyses also revealed that the interaction of press-ups and jump ability improved the prediction power of AC (R2=0.44, p=0.004, 95% confidence intervals=0.009–0.04). Pearson’s correlation coefficients detected significant negative correlations between the mean score recorded for injury severity (expressed as TDO) and lower body muscular power (r=-0.66; p=0.014); backward regression analysis also revealed that, from all studied parameters, the strongest predictor of TDO was lower body muscular power (p=0.014). For the intervention group repeated measures ANOVA revealed significant increases (pre vs. post) in aerobic fitness (p<0.05), lower body muscular power (p<0.05), upper body muscular endurance (p<0.05) and performance (p<0.05). Linear regression analyses indicated that the only significant predictor of AC was aerobic capacity (F=7.641; p=0.03); the interaction of press-ups and aerobic capacity (F=6.297; p=0.036), and lower body muscular power with aerobic capacity (F=5.543; p=0.05) demonstrated an improved prediction power. These results show that the observed contemporary dance performance is an intermittent type of activity of moderate intensity. Given the reliability of the AC tool, it is concluded that upper body muscular endurance and jump ability best predict AC of contemporary dancers. Reduced lower body muscular power is associated with increased severity of injuries. Finally, supplementary exercise training significantly increases lower body muscular power, upper body muscular endurance and aerobic fitness, which in turn are beneficial to improve AC of contemporary dancers.

The overall goal of the thesis was to develop and optimize the moving bed biofilm reactor technology under anaerobic conditions. The thesis work was divided into two different series of experiments. Hence, at first, the reactor start-up on synthetic substrate was evaluated and it was proven that the anaerobic moving bed biofilm reactor technology could successfully treat concentrated wastewater. Subsequently, a study on Fort Garry Brewery wastewater was conducted to optimize the process for a typical North American industrial wastewater. The aim was successfully achieved and a potential design to treat Fort Garry Brewery wastewater was developed. The anaerobic moving bed biofilm reactor was found to be capable in treating brewery wastewater with potential savings to the industry paying surcharges for discharging wastewater over the city sewer bylaw limits. / October 2016

A number of advanced pre-treatment techniques and methods have been evaluated for the sole purpose of improving digestibility of waste activated sludge. The pre-treatment of waste activated sludge (WAS) offers the benefit of releasing solubilized substrates, making them readily available to be utilized in the anaerobic digestion process. Other potential benefits include: reducing shock loading to the digester, improving overall digestibility and potentially providing filament / foaming control. Chlorine dioxide, a well-known disinfectant and oxidizing agent has been utilized in many drinking water processes around the world. Its use in wastewater treatment processes however is limited; especially in Canada where legislation has prevented its use for final effluent disinfection. As an oxidizing agent, chlorine dioxide induces cell rupture resulting in the release of soluble material, which when fed into the digester, may serve as readily available substrate for active microorganisms. This mode of action creates the potential for chlorine dioxide to be used as a sludge pre-treatment agent to improve digester performance and in alleviating pre-existing filamentous sludge bulking. This study was conducted using waste activated sludge obtained from the City of Winnipeg’s South End Water Pollution Control Centre (SEWPCC), with the following objectives: 1. Determine the efficacy of chlorine dioxide in alleviating pre-existing filamentous sludge bulking; 2. Determine chlorine dioxide ability to increase WAS solubilization; and 3. Define impact of chlorine dioxide on anaerobic digester performance. WAS pre-treatment using chlorine dioxide was found to be effective in alleviating filamentous bulking. This is significant as filamentous bulking in the activated sludge may lead several problems downstream. Following pre-treatment, sludge bulking was determined to be alleviated as observed by photomicrographic evidence and as measured by a 57% decrease in the stirred sludge volume index (sSVI). Particulate COD solubilization increased by 60%, 76%, and 74% over the untreated sludge for WAS pre-treated with 25, 50, and 100 mg ClO2/L (v/v), respectively. The pre-treatment of sludge using chlorine dioxide did not have any negative impact on digester performance although it also did not lead to improved performance. The volatile solids destruction and COD removal remained unchanged for both untreated and pre-treated sludge. Chlorine dioxide pre-treatment did not affect anaerobic digestion even at the lowest SRT evaluated; it is possible to decrease the digester SRT to as low as 6 days while maintaining the solids destruction and COD removal capability. Biogas production did not improve with increasing chlorine dioxide dosage during pre-treatment but also was not hindered by the pre-treatment agent. Chlorine dioxide was shown to alleviate filamentous bulking and improve solubility and has the potential to improve digester performance without negative impacts to the digester. However, the full benefit of the pre-treatment method may only be realized for complex “difficult to disintegrate” sludge types. / October 2016

This thesis explores the details and profitability of two distinct operational strategies utilized by dairy operations as alternatives to expanding milk production. It features farms that have either transitioned to organic production or installed a farm-scale anaerobic digester, motivated in part by the opportunity for market specialization or income diversification to increase the viability of their dairy farm businesses. The first analysis examines the demographics and production characteristics impacting the profitability of organic dairy farmers in Vermont and Maine. This provides policymakers, educators, lenders, and suppliers with a profile of this sector that accounts for 23% of dairy farms in Vermont and 20% of dairy farms in Maine, annually shipping, on average, 787,600 lbs. milk per farm. The study was conducted through a longitudinal survey of 83 organic farmers in Vermont and Maine from 2004 to 2012. A multiple linear regression analysis of the sample demonstrated six significant variables that affect farm profitability measured by return on assets (ROA). Having at least 80% Holstein herd composition, increasing the daily pounds of grain fed to cows during the winter months, a primary farm operator having grown-up on dairy farm, and the use of feed mixing machinery all positively impacted ROA. Farm profitability was negatively affected on farms with a high rate of annual cow morbidity and also tended to decrease over the course of the survey as organic prices leveled. While the model developed here has some explanatory power (R2 = 0.387), variability in farm profitability is affected by complex economic pressures. The second analysis reports the predicted and actual annual maintenance figures collected from anaerobic digester systems in Vermont. Within Vermont, 16 farms operate methane-generating ADS. All of these farms have received some form of public funds and/or a voluntary consumer premium. The analysis compares costs by creating a ratio of actual maintenance, repair, oil, and labor costs over these same predicted costs. This ratio is used to assess whether the suggested industry operating cost estimator tends to over or under predict annual maintenance costs. The ratio was evaluated with a one-way Student's t-test (p = 0.046) finding that maintenance costs tend to be under-predicted compared to the actual costs. One-way ANOVA was used to determine a statistically significant effect of herd size (F = 6.453, p = 0.052), showing that the maintenance ratio varies significantly between groups, This analysis indicates that predicting annual maintenance, repairs, and labor costs as a function of 3.5% of total kWh production is an acceptable method for digesters on farms with more than 500 cows, but under predicts maintenance costs for smaller farms. For smaller farms, the actual costs were on average 2.5 times higher.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.